1. Technical Field
The present invention relates to vehicle audio systems. More particularly, the invention relates to a system and method for updating the software of a digital amplifier after installation in a vehicle.
2. Related Art
A typical vehicle audio system includes a head unit, an amplifier and speakers. The head unit may have several audio devices, such as a CD (compact device) player, a radio tuner, a tape player and an MP3 player. Typically, the head unit outputs an analog audio signal to the amplifier. The amplifier can control the volume, balance, tone and distortion limits, fade and equalization parameters of the audio signal. In addition, the amplifier drives the speakers with the audio signal.
In recent years, consumer expectations regarding the performance of vehicle audio systems have increased. This has resulted in an increased use of digital amplifiers. Digital amplifiers typically have a digital signal processor (“DSP”) to provide digital processing of audio signals received from the head unit. The DSP provides audio processing features, such as delay, surround decoding, non-causal filters and fast equalization updates.
However, digital amplifiers contain software that may need to be updated. For example, an amplifier may need a software update to enhance its operation or fix a flaw discovered after the start of production. A digital bus may be used to transmit the software updates to digital amplifiers. For example, a controller area network (CAN) or optical bus, such as the MOST bus, could be used to update the software in the amplifier.
Unfortunately, the use of a digital bus for software updates is not always possible. For example, the amplifier may not support a digital bus. In addition, the vehicle may not have a digital bus. In these circumstances, there is no practical way of updating the amplifier's software short of removing the amplifier from the vehicle, which is a difficult and time consuming process. Therefore, a need exists for a system and method for updating the software of a digital amplifier without using a digital bus.